If chkdsk is not working than you could try to format the card and then run a recovery program. This worked for me.

I had the exact screen as you.

First try running just chkdsk X:
To ensure that the computer is reading the disk (for me it read but said that there were errors).
When I tried to run the /f and /r function the program stopped working.

In a last ditch effort I formatted the card and ran recuva on it and was able to recover all my files and the card is now usable again.

If you take the reformat and then run file recovery approach - - - PLEASE be kind to yourself and during the reformat step, be sure to use QUICK FORMAT which will correct the partition table and the Free vs. Allocated lists but not rewrite every sector.